A technician cannot get link on a freshly punched-down jack for a new clinic exam room, but a cable tester shows continuity on all eight conductors. Tracing the run at the patch panel reveals the pairs were terminated in a different pin order than the standard used at the wall plate. What is the most likely explanation for the failed link?

Structured cabling relies on both ends of a run following the same termination standard so that the correct wire pairs line up with the correct pins for transmit and receive; continuity testing only confirms that each individual conductor is electrically connected end to end, not that the pairs are terminated in a way that produces a working link. Mixing termination standards between the wall plate and the patch panel can misalign which pairs carry which signal, which is a physical-layer wiring defect that a basic continuity test will not reveal, since the wires are still connected, just not in the arrangement the electronics expect. A VLAN misassignment on the patch panel port is meaningless in this context, since a patch panel is a passive wiring device with no VLAN configuration at all; VLANs are configured on the active switch port. A spanning-tree port stuck in blocking state assumes the link is already physically up and being managed logically, which contradicts the fact that no link exists here. A Layer 3 routing loop is a much higher-layer concern that requires functioning links to even occur, so it cannot explain a link that fails to come up at all. A concrete check is re-terminating both ends to the same wiring standard and confirming with a wire-map or link-light test rather than relying on continuity alone.